I'm building a #WSPR transmitter using a #Nodemcu controller, #SI5351 clock generator and GPS module for precise timing. I testet the prototype today. The HF PA uses three BS170 mosfets in parallel and is driven from the 3.3V of the Nodemcu. I did a quick check with my thermal camera. Temperature reading of the BS170 is 75 degree C after 20 seconds. But the more concerning temp reading comes from the Nodemcu having hotspots in the 100° C range. Not good.
#hamradio #diy #electronics